Compared with an amorphous-silicon Thin Film Transistor (a-Si TFT), a technology of low temperature polycrystalline silicon has many advantages, such as a high mobility which is between 10 and 100 cm2/Vs, meanwhile capability of being manufactured at low temperature (less than 600° C.), and being adapted from flexibly chosen substrate, and thus is currently the only active layer manufacturing technology that can be compatible with a flexible display technology. But now the technology currently adopts a strip laser beam to scan, and polycrystalline silicon using a temperature difference between adjacent scanning lines during the scanning process. Although such method can produce a relatively uniform polycrystalline silicon thin film, a slow scanning speed restricts manufacturing of large-area displays, and meanwhile production efficiency is low, and production cost is increased.